Dry kiln



April 30,4 1.929. H. H. PAYzANT DRY KILN Filed oct. 24', 1925 5 Smets-Sheet L) TTORNEY Patented Apr. 3o, 1929.

UNITED STATES 1,711,100 PATENT OFFICE.

HENRY nanars PAYZANT', or nvnaafrm, Wasilla-Grou.

g DRY nur.

.Application led October 24, 1935.4 Serial No. 64,528.

j ject of the invent-ion being to provide means for preventing over dryin rious to the product, or un er drying which is not desirable especially when the lumber is to be shipped as it means the paying of freight, charges on excess moisture which amounts to a considerable item when large shipments of lumber are concerned.

More specifically, the'object of the invention is to provide a dry kiln having a weighing mechanism therein whereon truck` loads of lumber may be positioned as they are advanced progressively through the kiln so that, when the weight of a load has been suilciently reduced by evaporation, incidental to drying, the weighing mechanism will move in such manner as to effect the closing of circuits to electric motors which are thereby set in motion to open the kiln doors and withdraw the load of lumber from the drying chamber.

Another object of the invention is to pro vide for 'the advancement of the lumber trucks progressively through the kiln in ac cordance with the opening and closing movement of the doors so as to avoid as much as possible the loss of heat from the kiln during the intaking'and withdrawing of lum er and to give to each truck load the exact mount of seasoning required.

A still further object is to provide means whereby the heat within the kiln willbe auto-l matically cut off whenever the load farthest advanced in the drying has reached a predetermined degree of dryness.

Other objects of the invention reside in the various details of construction and combination of parts, as will hereinafter be described.

In accomplishingr these and other objects of the invention I have provided the improved Idetails of construction, the preferred forms of which are illustrated in theaccompanying drawings, wherein- Figure 1 is a vertical section, longitudinally of a drying kiln that is equippedw-ith mechanism embodied by the present invention, also showing diagrammatically the wiring for the various electrical devices.

Figure 2 isv an enlarged, detail view of motor controlling switch mechanisms that are which is inju-l to ,be operated by movement of one of the kiln doors.

Figure 3 is a det-ail view ofthe ratchet lock mechanism for one of the cable winding drums and the switch and trip mechanism in connection therewith.

Figure 4 is a cross section view of the kiln.

Figure 5 is a detail view of the switches operated by the weighing device.

Figure 6 is a longitudinal, sectional view` of a kiln of an alternative construction.

Referring more in detail to the drawin sl designates the drying chamber of a iln that is especially designed for the drying of lumber; the latter to be arranged in stacks on wheeled trucks that are moved into and from the kiln on a track. The kiln comprises the opposite side walls 2 and 3, opposite end walls 4 and 5 and a roof 6; the latter being sloped toward one end of the kiln and provided at its higher end with a stack 7 that maybe equipped with a suitable damper for controlling the'4 escape of heated air from the drying chamber. At opposite ends of the kiln are suitable openings 9 and l0 fitted, respectively, with vertically sliding doors 11 and 12.

Extending lengthwise of the kiln and through the openings 9 and 10 is a track consisting of parallel rails 13 on which wheeled lumber trucks 14 are adapted to travel into and from the drying chamber. The track is elevated above the Hoor of the kiln and is supported by cross beams 15 and posts 15 and electric heating elements of a suitable character, as designated at 16, are located atjopposite sides of the chamber below the level of the track which su ply the heat for drying the lumber that is Ibrought into the chamber.

The kiln whirih I have illustrated is designed to accommodatethree truck loads of `lumber and the drying chamber may be all 1n one compartment for treatment of entire change or may be divided into a plurality of compartments for progressive treatment of the loads. The kiln, however, may be of any size and contain more than one track with as many loads as may be accommodated. The trucks on which the lumber is loaded are connected entrain for progressive advancement into and from the kiln, enterin through the opening 9 and leaving throug the opening 10, Adjacent the exit 10, within the kiln therev is a short section of track designated at 20 that is mounted on a weighing platform 21 to which a scale beam 22 is connected vin the usual manner and a weight the presentdevice is as follows: Since it is known that a given number of feet of seasoned, or dried lumber of a certain species should have a certain weight when properly dried, it requires but a simple computation to determine what each truck load of unseasoned lumber that enters the kiln should weight when suiiciently dried, taking into consideration the weight of the carrier. Itis appa-rent, then, that by adjusting the weight 23 on the scale beam 22 at that certain predetermined weight aft-er a truck load of lumber has been advanced onto the scale platform, it can be determined when that degree of dryness has been reached for, at that time, the beam will fall.

In order that doors may be opened for the advancement of the trucks of lumber into and from the kiln and the operation automatically controlled, I have provided an electric motor 25 which preferablyis located centrally of the kiln below the track, as is shown in Figure 1, and which is operatively connected to rotate a drum 26 on which the ends of cables 27, 28 and 29 are wound. The cables 27 and 28 extend upwardly and over guide wheels 30 and 31,1espectively, toward opposite ends of the kiln, then over guide wheels 32 and 33 and downwardly and connected at the lower edges of the doors 11 and 12, respectively. The connection is such that when the cables are wound onto the drum 26 the doors will be lifted to open posi tion. The cable 29 likewise extends upwardly from the drum and then over a guide wheel 34 and is connected at its end'to the lower edge of a vertically sliding door 36that is adapted, when lowered, to close off a compartment in the drying chamber adjacent to the exit of the kiln and in which the scale platform or weighing device is contained.,

The electric circuit for the motor 25 is turned'on and oif under the control of a switch that is operated by movement of the scale beam and another switch under the control of movement of the exit door 12. The first switch mentioned, shown best in Fig-ure 5, preferably consists of a mercury .container 38 into and from which slidably supported bar 39 will be moved, in accordance with the downward and upward movement of the scale beam, through a connection consisting of a pivotally mounted lever 40, as shown in Figure 1. The ydoor controlled switch, shown best in Figure, 2, comprises a pivotally supported bell crank 41 equipped with a roller 42 at one end that is held by a suitable spring in rolling contact with the door 12 and equipped with a contact 43 at its other end that, so long as the door is not fully opened, is held thereby engaged with a fixed contact 44, as shown in Figure 1. A circuit wire 45 connects the contact 44 with the switch bar 3S). Another wire 46 connects the mercury cup 38 with one side of the motor 25, A source of electricity, which I have designated at 48, has one pole connected to theother side of the motor 25 by a circuit wire 49 and its other pole connected by circuit wire 50, through a control switch 51, with the contact 43 on the switch crank.

With the above arrangement, when a load of lumber, disposed on the scale platform 21, has been lightened bycdrying to the certain predetermined weight, the scale mechanism will be moved and through vthe intermediacy of the connecting lever 4() the bar 39 will be projected into the mercury in cup 36 thereby vclosing a circuit through the motor 25 causing' it to rotate the drum 26 to wind in the cables 27, 28 and 29 to simultaneously raise the doors 11, 12 and 36. When the door 12 has reached its upper limit of travel, it disengages the roller 42 of the bell crank 41, allowing the bell crank to disengage the contact 43 from the contact 44 thereby again openin g the circuit. to stop the motor. Then, to prevent the doors moving downwardly under their own weight after the circuit is thus opened, I have provided a ratchet wheel 53 ('see Figure 3) on the end of the drum shaft 54 which is engaged by a tired pawl 55 to prevent unwinding.

After the doors of the kiln have been raised to the required height, the finished truck load of lumber is withdrawn and thc others are ad vanced in the kiln. For this purpose I have provided an endless cable 60 that extends longitudinally through the kiln about guide wheels 61 and" 62 .at its opposite ends and about a drum 63 that is located within the kiln below the track and which is adapted to be rotated by an electrically driven motor 64. The several lumber trucks 14 are connected with the upper run of the cable by any suitable means which permits them to be easily .and readily connected or disconnected.

The motor 64 operates under the control of switch mechanismswhich are actuated bythe door12 and the truck of lumber being removed so that it operates only when the doors are open. The motor has one pole connected to one side of the source of electricity by means of a circuit wire 70. The other pole of the motor is connected by circuit wire 71 with a switch contact 73 disposed closely adjacent and normally electrically connected with a Contact 74 which is connected by cir cuit wire 75 with a contact 76 disposed in such spaced relation to the contact 43 on the Vlever of the door actuated switch, shown in Figure 2, that when the door is opened suiicientl;7 to disengagethe roller 42, the contact 43 will move to a position against contact 73. The wire 50, through switch 51, then completes the connection to the source of elec- Y ances.

tricity. A pivotally mounted switch lever 78 normally engages contacts 72 and 73 to conneet them electrically and this lever has an arm 79 extended into the path of movement of the trucks withdrawn from the kiln so that it will be moved by the trucks to open the circuit. The lever 78 also is equipped 'with an arm 80 to which one end ofa cable 8l is connected; the cable extending to the pawl 55 and connected ltherewith so as to trip the pawl to release the ratchetand ermit unwinding of the drum and lowering of the doors at the proper time after the withdrawal of a load. J

The switch mechanism above described provides that the circuit to motor 64 is normally open but after the weighing mechanism has moved to cause a circuit tobe closed through motor 25 and the kiln doors to be raised, the

door actuated switch contact 43 engages con-- tact 76 to close a circuit through motor 64 to rotate the drum 63 whereby, through cable 60, the trucksare advanced. As the truck that is being removed moves from the kiln its forward wheel engages the trip lever 79 of switch 78 and moves the switch so as to disconnect the ,contacts 72 and 73 so that the circuit is opened Nand the motor stopped after the 'several trucks have been advanced one interval. Movement of the switch lever 78 also through cable 80, trips the pawl 55 so that the doors may move lto closed positions as before described.

The several heating elements 16 are connected to the source of elect-ricity through a suitable switch mechanism designated at which operates under the control of the weighing mechanism. to cutoff the circuit whenever the weighing mechanism moves downwardly incidental to suiiicientdryin of the load thereon. The switch preferily would consist of a sliding bar 91 connected to lever 40 and adapted to be projected into a mercury cup 92 by the movement of a load of lumber into the scale platform 21. The opposite sides of the heating elements are connected to the switch parts 91 and 92 through circuit wires 94 and 95 as shown in Figure l.

It is evident that the motors, scales and beams may be located in any place suitable and convenient and may be of any type adapted to perform the,required functions. The measuring switches may be of the open pan or tube design, while the doors may be raised and lowered. or swung open and shut by means of worm reduction gear thus avoiding the use of ratchets and other brake contriv- The kiln may be heated electrically or by other means. e tracks maybe level or inclined and the doors may be opened and closed manually. A kiln constructed to show the charge systemofdrying all loads at one time and with the motors located outside of kiln is illustrated in Figure 6, as an alternative construction.

operable under the control of movement of said support incidental to change in weight of the material due to drying for moving the doors from closed to open position.

2. In a dry kiln of the character described, a drying chamber having doors for the intaking and removal of material, an electric motor foractuating the doors from closed to open position, an electric circuit for the within the drying motor, a weighing device chamber on which the material may be placed for drying and a control switch for said circuit 'operatively connected .to said weighing device to be actuated thereby to close a circuit through the motor after a predetermined decrease in the weight of the mai teri al due to its dr'ying.

3. In a drykiln ofthe character described,

a drying chamber having doors for the intaking and removal of material, an electric motor for actuating the doors from closed to open positioman electric circuit for themotor, a weighing Adevice within the drying chamber on which the material may be placed for drying and a control switch for said circuit operatively connected to said weighing `device to be actuated thereby to close a cir "cuit through the motor after a predetermined decrease in the weight of the material due to its drying and means operable by the door when it is fully opened to open the motor circuit.

4. In a dry kiln of the character described, a drying chamber having doors for the intaking and removal of material, electric heating elements within the chamber, an -electric motor operable to move the doors from closed to open position, a scale platform within the chamber on which material to be dried may be placed, a scale mechanism connected with the platform whereby the `material may be weighed and embodying an adj ustable means that may be set for movemet after a predetermined decrease inthe weight of the material incidental to drying, an electric circuit for the heating elements and motor and switch mechanisms operable by movement of the scale mechanism after a setting has been made lto close a circuit through the motor and open the circuit to the heating elements.

5. In a dry kilnl of the character described, a drying chamber having vertically movable doors for the intaking and removal of material, an electric motor for raising the doors,

an electric circuit for the motor, a weighing device 'within the chamber on which the material may be placed while being dried, a control switch for the circuit operatively connected to the Weighingdevice to close a circuit through the motor to open the doors after there has been a predetermined decrease in the Weight of material incidental to drying, means operable by the door to open the circuit -When the door is fully open and releasable means tor retaining the 'door in open position after the circuit is opened.

6: In a vdry lkiln of the character described,

' a drying chamber having vertically movable doors, an electric motor for raising the doors, a track through the kiln on which Wheeled trucks of material may be advanced through the kiln, an electric circuit for the motor, aI `weighing device interposed in the track -Within the kiln on which the trucks of material may be placed for drying, a control switch for 'the circuit operatively connected to the weighing device to close a circuit through the motor to open the doors after a predetermined decrease in the Weight of material, means operable by the'door to open the circuit when the door is fully open and a locking device ffor holding the doors open after the circuit is opened and a trip mechanism for the locking device operable by trucks on leaving the kiln. r

7. In a dry kiln of the character described,

Aa drying chamberhaving doors for the intaking and removal of material, a yieldable support Within the chamber on which material to be dried may be piled and means operable under the control of movement of said supportincidental to change in Weight of Athe material due to drying for movin the doors from closed to open position an means for successively-advancing trucks of material ent-rain through `the kiln in synchronism lWith opening and closing of the doors.`

8. Ina dry kiln of the character described, a drying chamber having doors for the intaking and removal of material, an electric motor for actuating the doors from closed to open position, an electric circuit for the motor, a weighmg device within the drying chamber on which the material may be placed for drying and a. control switch for said cireuit operatively connected. to said Weighing device to be actuated thereby to' close a circuit through the motor after a predetermined decrease in the Weightl of the material due toA its drying, an endless cable extended through the kiln to which trucks may be attached `for advancement entrain through the drying chamber, an electric motor J`for advancing the cable, and switch mechanism operable by the kiln door for closing and opening the circuit to said motor.

Signed atI Everett, Snohomish County, Washington, `this 23rd day of September', 1925.

HENRY HARRIS PAYZANT. 

